Shear pin cutout for stoker motors



OOtvll/lw w r a 5 DELMOND L. GETZ D L GETZ SHEAR PIN CUTOUT FOR STOKER MOTORS Filed March 16, 1950 Feb. 10, 1953 Patented Feb. 10, 1953 UNITED STATES PATENT OFFICI'E- SHEAR. PIN CUTOUT FOR STOKER' MOTORS Delmond L, Geiz, Springfield, Ohia, assignor. to. The Steel Products Engineering Company, Springfield; Ohio; a corporation of Ohio,

Applicationltiarch 16, 1950,. Sofia-1N0; 149,953?

(Cl. Mt e-475) 3' Claims. 1

This. invention relates-to stoker systems and more. particularlyto asafety drive for the operation of the stoker.

In the ordinary stoker system such as thatused for domestic, and the small industrial installations; it is common torprovideadrive motorfor operatinga blower and fuel feeding mechanism under the control of athermostat or other regulating mechanism in order to maintain a desired. temperature, or pressure, condition within an enclosed space. For safety purposes it is likewise the practice toutilizea shear pin in. the driveunit. for coupling the driving and driven members. together, the. pin having'such size. and shape, and corresponding. strength that it will release or shear whena load in excess of a safe value is encountered. For instancaif apiece of iron or other solid object is present in the body of fuel, its entry into the fuel supply means may cause. damage, andto prevent this from arising the shear pin construction isemployed.

'iherupturev of the shear pin serves to prevent damage to the drive mechanism, butunless some additional provision is made, the. drive motor would normally continue in operation. This would not only unnecessarily continue the. operation. of the motor without accomplishing any feeding of fuel, but it would continuetheblower 2 sultv lira dangerous or damagingburning out the fuel still in. the retort, the drive is stopped and there is no further supply of either fuel or air, and the entire system is thus fully protected.

It is also a feature of the invention that inresponse to suchoperation, an indication or signal is afforded, either. audible or visual, or both, so that the attendantor house occupant. will know of the condition, and can take the necessary steps to clear the obstruction, and restore thesystem to operation.

It is therefore a principal objectof the invention to provide a stoker. control systemin. which in operation and'this would resultin the burning down of the. fuel remainingini the. retort. In the absence of afresh and continuing supply of fuel, the. existing fuel bed would quickly become thin, andsoonburn out entirely, with the. development ofexcessive temperatures and possible damage to the retort or tuyeres.

In accordance with thepresentinvention, the shear pin is coupled with additional actuating mechanism which has a normal position in which the stoker system. continues 1 to operate in: allrespects under-itsusual controls such astemperature, pressure, orthe like regulation. However in the event that the shear pin is;broken, there isa resultant relative rotation .betweenthe driving member which continuesto. operate-for a short interval, and the.driven,. member coupled to the fuel supply means "which nolonger-openates because of the rupture of; the shear pin. As a. result of thisrelative. rotation between thedrive ing and thedriven members, the actuatingdevice is shifted away fromv its normalpositlon and this causes the operation of acontrol Which is effec: tive to stop the operation-of the drive and con sequently ofthe blower. Thus within-a short in.- terval after the rupture of the shearqpin; which interval is much less than that which could rethere is provision for stopping, the-operation of the system upon the breakage. of. the shear pin thereby not only assuring against damage to the feeding structure, but preventing anydamage to the retort, by reasonof the burning out of the fuel bed thereon.

Itis a further object to provide. such a system incorporatinga visual'or audible. indication of such breakage and'the fact that the system is no longer in operation.

It is a still further object to. providesuch an arrangementwhich issimple in construction and which can be readilyinstalled both. on newequipment and likewise on existing equipment already in use.

Other objects and advantages will be apparent from the following description, the-accompanying drawings andtheappended claims.

In the drawings Fig. 1 is a side elevational viewwith parts bro ken awayshowing. a typicalv stoker installation embodying a hopper and the fuel supply means for delivering the fuel to theretoit;

Fig. 2 is a vertical sectional view on .a larger scale showing the mechanism. in accordance with the invention which is associated with theshear pin,the parts being in the normal driving relationship;

Fig. 3 is a view similar to Fig. 2.,but showing the parts following the rupture of the shear pin;

Figs. 4 and 5 are vertical sectional views on the lines 4.4 and 55 respectively of.Fig..2; and

6 isa diagrammatic .view showing the circuit connections for use inthe operation of the system.

Referring to the-drawings which disclose a pre ierred embodiment of the invention, Fig. 1 shows. a side view of a stoker installation in which there is a fuel receiving hopper In having a supply cover ll through. which. it maybe loaded with coal or other :solid fuel. The drive motoriis 111+ dicated at 12 having a V-belt drive [3 to a pulley 3 H5 mounted on gear case l5. Various types of gear mechanism may be employed providing for the operation of the feed worm it at a suitably slow rate of speed. Preferably the mechanism is one which will advance the feed worm through intermittent steps of movement, and may embody a ratchet drive mechanism such as that described in copending application Serial No. 126,962, filed November 14., 1949, and assigned to the same assignee as this application. The feed worm extends through the lower part of the hopper Ii), where it picks up the fuel and delivers the same into the retort I8 where the burning takes place.

Pulley it also provides for the operation of a blower or fan indicated at 28 which supplies air under suitable pressure through wind tunnel 2i and from it into the tuyeres 22 in the retort.

Referring more particularly to Fig. 2, the outside wall of the gear case I5 is shown as receivin a ball bearing 30 which rotatably supports sleeve 31 to which is connected a driving gear 32 having ratchet teeth 33 thereon. Suitable mechanism is provided in the gear case [5 for the rotation of gear 32 in a series of step-by-step movements, under the control of the time and temperature or pressure mechanism, in order to accomplish the desired temperature regulation. The sleeve 35 has a portion 35 which extends outwardly of the gear casing, suitable packing 38 being employed to prevent escape of lubricant from the bearing til. Rotatably mounted within the sleeve M is the driven member or shaft 59 which is directly connected to the feed worm l6, providing for the operation of the worm when the shaft is turned. The shaft 49 has an overhanging end portion ii which is squared or of other noncircular shape by means of which it can be turned by hand in case of necessity.

In order to couple the driving member or sleeve 31 with the driven member or shaft 40, a shear pin 25 is provided which is of suitable length to extend through correspondingly aligned bores in both the sleeve and the shaft. Thus when so assembled, the shear pin acts as a connecting link and transmits the driving torque from the sleeve to the shaft. When however the feed worm encounters a heavy obstruction and further turning of the shaft is is prevented, the strength of the shear pin is such that it will then rupture before any damage occurs with respect to the mechanism itself. This effectively interrupts the drive for the fuel feed mechanism, but does not stop the drive motor and thus the blower 26 remains in operation, continuing to supply combustion air to the retort with consequent objectionable burning out of the fuel bed.

In order to prevent such objectionable condition an actuating member in the form of a sleeve 5% is mounted upon the overhanging end of drive sleeve 35, sleeve 56 having an intermediate outwardly extending flange 5i and oppositely aligned apertures 52 which receive the outwardly extending ends of shear pin it, this relationship being clearly shown in Fig. 5. Also, one side of each end of the shear pin is provided with a fiat indicated at 53 and this flat is adapted to be received beneath the overhanging flange 5! of the actuating member so that when the partsare in the position shown in Fig. 2, the shear pin is positively locked in position and cannot drop out as it revolves even though there may be no frictional force between the driving and the driven memhere.

This is the normal position of the actuating member '56, and order to retain it in that i position, a biasing means is provided comprising a compression spring 55 which abuts against a collar 58 secured bymeans of set screw 51 to the squared end ll of shaft 4c. Normally, therefore, the actuating member 50 occupies the position shown in Fig. 2 in which the pin 45 is prevented from falling out of its driving position.

It is desired to provide for movement of the actuating member 5% axially of the sleeve 35 in response to the rupture of the shear pin. For this purpose the inner face of the disk portion 68 of the sleeve 56 is provided with cam surfaces Bl in the form of a flat V, on opposite sides of the shaft dd. A pin 52 is fixed in shaft 45 and lies normally at the bottoms of the V-shaped groove formed by these cam surfaces. This allows the actuating member 58 to move to its normal righthand position as shown in Fig. 2 for continuing operation of the stoker.

In response to the rupture of the shear pin, the outer ends of the pin break oif from the inner part which remains in shaft is, and while shaft it immediately stops, the drive member or sleeve 3! continues to be driven by the drive motor. Since the outwardly projecting end of the shear pin 35 remains in interfitting relation in' slot 52, it is evident that the drive between sleeve 35 and the actuating member 5% will continue. Thus the sleeve rotates, in progressive increments or steps in the type of drive mechanism referred to above, and as this rotation continues, the pin t2 fixed in the shaft is now forced up along the cam surfaces 6! of disk 68. As this relative rotation progresses, therefore, the disk 69 and the actuating member 59 will be cammed away from the sleeve, or toward the left as shown in Figs. 2 and 3, thereby shifting the position of the actuating member and causing it to pull away from the broken ends of the shear pin, to such a point that the shouldered portions 53 are no longer locked beneath the flange of the member 5i. This allows for access to and withdrawal of the broken ends of the shear pin, or the same may fall out by gravity if they are downwardly positioned.

A control switch indicated at E6 is mounted in suitable location adjacent flange 5i and arm "ii pivotally connected with the switch is engaged by such flange 5!. The circuits of the control switch it are indicated in the diagram in Fig. 6. The normal circuit is completed through switch arm '52 which supplies an energizing voltage to the operating solenoid of a relay which closes the main motor circuit at it, under the control of various timers. thermostats, pressure, safety 7 and such other control mechanism as is normally provided, all such control devices being indicated diagrammatically and marked T. It will be'understood that in the normal operating condition with the actuating member 50 in its righthand position as shown in Fig. 2, switch 12 remains closed and the system operates in all respects in a normal manner.

The switch 76 has another contact arm and this contact is normally open but closes when the parts occupy the alternate position as indicated in Fig. 3. Not only does this movement result in opening switch 32, causing the stoppage of the motor and of the driving operations as well as stopping the operation of the blower, but it also completes a circuit to indicating mechanism diagrammatically illustrated as a visual indicator 75 and an audible indicator 17, either or both of which may be employed. Thus upon the occurrenceof the fracture of the'pin, the drive is cut off and an indicating signal energized so that the attendant may be advised and take the proper steps to restore the system to use.

In such restoring operation, after first clearing the obstruction from the feed Worm, the actuating member 59 is preferably rotated to bring its slot 52 into alignment with the remaining portion of the shear pin within the shaft 4t, and the remaining piece of the broken pin removed and a new pin inserted. The actuating member 56 is manually held against the spring 55 during this operation, and when released, it will move into the interlocking position shown in Fig. 2 under the spring action. This restores the system to its original position of operation, and at the same time results in the cutting of? of the warning signals and the reenergization of the relay '13, thereby placing the operation of the system fully under the other controls '1, for continued operation in the usual way.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. In a stoker system for supplying fuel and combustion air to a retort, the combination of a driving member in the form of a sleeve, a driven member in the form of a shaft within said sleeve, a shear pin extending through said sleeve and said shaft and normally coupling said driving and said driven members together, an actuating member loosely mounted on said sleeve and having parts driving-1y engaged by said shear pin to normally cause rotation of said actuating member with said driving and driven members, means on said actuating member overlying and retaining said shear pin in assembled position, means for yiel-dably biasing said actuating member toward a normal position overlying said shear pin, means positively operable upon relative rotation between said driving member and said driven member for moving said actuating member on said sleeve following the shearing of said pin, and control means engaged by said actuating member upon movement thereof to terminate the operation of said system.

2. In a stoker system for supplying fuel and combustion air to a retort, the combination of a driving member in the form of a sleeve, a driven member in the form of a shaft within said sleeve, a shear pin extending through said sleeve and said shaft and normally coupling said driving and said driven members together, an actuating member movably mounted on said sleeve and having parts overlying portions of and drivingly engaged by said shear pin, said shear pin having a shoulder engaged beneath said actuating member in the normal position of the latter providing for locking said pin in operative position, a biasing spring urging said actuating member axially of said sleeve and normally maintaining said actuating member in said overlying position with respect to said pin, camming means operably carried by said actuating member and said driven member and operable upon the shearing of said pin and the resultant relative rotation of said driving member and said actuating member with respect to said driven member for camming said actuating member away from said normal position, and means operative in response to said movement away from said normal position for stopping the operation of said system.

3. In a stoker system for supplying fuel to a retort, the combination of a driving member in the form of a sleeve, a driven member in the form of a shaft within said sleeve, a shear pin extending through said sleeve and said shaft and normally coupling said driving and said driven members together said pin having a part extending outwardly beyond said sleeve, an actuating member movably mounted on said sleeve and having part-s drivingly engaged by said outwardly extending part of said shear pm, said shear pin having a shoulder engaged beneath said actuating member in the normal position of the latter providing for locking said retaining pin in operative position, a biasing spring normally maintaining said actuating member in said overlying position with respect to said pin, camming means operably carried by said actuating member and said driven member and operable upon the shearing of said pin and the resultant relative rotation of said driving member and said actuating member with respect to said driven member for camming said actuating member away from said normal position, and means operative in response to said movement away from said normal position for stopping the operation of said driving member.

DELMOND L. GETZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,929,994 Schlotman Oct. 10, 1933 2,022,007 Moore Nov. 26, 1935 2,037,260 Nelson Apr. 14, 1936 2,062,905 Hilty et a1. Dec. 1, 1936 2,113,666 Suman Apr. 12, 1938 2,147,220 Steinhour Feb. 14, 1939 2,283,467 Sco-ggin May 19, 1942 2,298,316 Simmons Oct. 13, 1942 

